class ActiveSupport::Multibyte::Chars

Chars enables you to work transparently with UTF-8 encoding in the Ruby String class without having extensive knowledge about the encoding. A Chars object accepts a string upon initialization and proxies String methods in an encoding safe manner. All the normal String methods are also implemented on the proxy.

String methods are proxied through the Chars object, and can be accessed through the mb_chars method. Methods which would normally return a String object now return a Chars object so methods can be chained.

'The Perfect String  '.mb_chars.downcase.strip.normalize # => "the perfect string"

Chars objects are perfectly interchangeable with String objects as long as no explicit class checks are made. If certain methods do explicitly check the class, call to_s before you pass chars objects to them.

bad.explicit_checking_method 'T'.mb_chars.downcase.to_s

The default Chars implementation assumes that the encoding of the string is UTF-8, if you want to handle different encodings you can write your own multibyte string handler and configure it through ActiveSupport::Multibyte.proxy_class.

class CharsForUTF32
  def size
    @wrapped_string.size / 4
  end

  def self.accepts?(string)
    string.length % 4 == 0
  end
end

ActiveSupport::Multibyte.proxy_class = CharsForUTF32

Attributes

to_s[R]
to_str[R]
wrapped_string[R]

Public Class Methods

consumes?(string) click to toggle source

Returns true when the proxy class can handle the string. Returns false otherwise.

# File lib/active_support/multibyte/chars.rb, line 75
def self.consumes?(string)
  string.encoding == Encoding::UTF_8
end
new(string) click to toggle source

Creates a new Chars instance by wrapping string.

# File lib/active_support/multibyte/chars.rb, line 51
def initialize(string)
  @wrapped_string = string
  @wrapped_string.force_encoding(Encoding::UTF_8) unless @wrapped_string.frozen?
end

Public Instance Methods

capitalize() click to toggle source

Converts the first character to uppercase and the remainder to lowercase.

'über'.mb_chars.capitalize.to_s # => "Über"
# File lib/active_support/multibyte/chars.rb, line 144
def capitalize
  (slice(0) || chars('')).upcase + (slice(1..-1) || chars('')).downcase
end
compose() click to toggle source

Performs composition on all the characters.

'é'.length                       # => 3
'é'.mb_chars.compose.to_s.length # => 2
# File lib/active_support/multibyte/chars.rb, line 180
def compose
  chars(Unicode.compose(@wrapped_string.codepoints.to_a).pack('U*'))
end
decompose() click to toggle source

Performs canonical decomposition on all the characters.

'é'.length                         # => 2
'é'.mb_chars.decompose.to_s.length # => 3
# File lib/active_support/multibyte/chars.rb, line 172
def decompose
  chars(Unicode.decompose(:canonical, @wrapped_string.codepoints.to_a).pack('U*'))
end
downcase() click to toggle source

Converts characters in the string to lowercase.

'VĚDA A VÝZKUM'.mb_chars.downcase.to_s # => "věda a výzkum"
# File lib/active_support/multibyte/chars.rb, line 130
def downcase
  chars Unicode.downcase(@wrapped_string)
end
grapheme_length() click to toggle source

Returns the number of grapheme clusters in the string.

'क्षि'.mb_chars.length   # => 4
'क्षि'.mb_chars.grapheme_length # => 3
# File lib/active_support/multibyte/chars.rb, line 188
def grapheme_length
  Unicode.unpack_graphemes(@wrapped_string).length
end
limit(limit) click to toggle source

Limits the byte size of the string to a number of bytes without breaking characters. Usable when the storage for a string is limited for some reason.

'こんにちは'.mb_chars.limit(7).to_s # => "こん"
# File lib/active_support/multibyte/chars.rb, line 116
def limit(limit)
  slice(0...translate_offset(limit))
end
method_missing(method, *args, &block) click to toggle source

Forward all undefined methods to the wrapped string.

# File lib/active_support/multibyte/chars.rb, line 57
def method_missing(method, *args, &block)
  result = @wrapped_string.__send__(method, *args, &block)
  if method.to_s =~ /!$/
    self if result
  else
    result.kind_of?(String) ? chars(result) : result
  end
end
normalize(form = nil) click to toggle source

Returns the KC normalization of the string by default. NFKC is considered the best normalization form for passing strings to databases and validations.

# File lib/active_support/multibyte/chars.rb, line 164
def normalize(form = nil)
  chars(Unicode.normalize(@wrapped_string, form))
end
respond_to_missing?(method, include_private) click to toggle source

Returns true if obj responds to the given method. Private methods are included in the search only if the optional second parameter evaluates to true.

# File lib/active_support/multibyte/chars.rb, line 69
def respond_to_missing?(method, include_private)
  @wrapped_string.respond_to?(method, include_private)
end
reverse() click to toggle source

Reverses all characters in the string.

'Café'.mb_chars.reverse.to_s # => 'éfaC'
# File lib/active_support/multibyte/chars.rb, line 107
def reverse
  chars(Unicode.unpack_graphemes(@wrapped_string).reverse.flatten.pack('U*'))
end
slice!(*args) click to toggle source

Works like String#slice!, but returns an instance of Chars, or nil if the string was not modified. The string will not be modified if the range given is out of bounds

string = 'Welcome'
string.mb_chars.slice!(3)    # => #<ActiveSupport::Multibyte::Chars:0x000000038109b8 @wrapped_string="c">
string # => 'Welome'
string.mb_chars.slice!(0..3) # => #<ActiveSupport::Multibyte::Chars:0x00000002eb80a0 @wrapped_string="Welo">
string # => 'me'
# File lib/active_support/multibyte/chars.rb, line 97
def slice!(*args)
  string_sliced = @wrapped_string.slice!(*args)
  if string_sliced
    chars(string_sliced)
  end
end
split(*args) click to toggle source

Works just like String#split, with the exception that the items in the resulting list are Chars instances instead of String. This makes chaining methods easier.

'Café périferôl'.mb_chars.split(/é/).map { |part| part.upcase.to_s } # => ["CAF", " P", "RIFERÔL"]
# File lib/active_support/multibyte/chars.rb, line 84
def split(*args)
  @wrapped_string.split(*args).map { |i| self.class.new(i) }
end
swapcase() click to toggle source

Converts characters in the string to the opposite case.

'El Cañón".mb_chars.swapcase.to_s # => "eL cAÑÓN"
# File lib/active_support/multibyte/chars.rb, line 137
def swapcase
  chars Unicode.swapcase(@wrapped_string)
end
tidy_bytes(force = false) click to toggle source

Replaces all ISO-8859-1 or CP1252 characters by their UTF-8 equivalent resulting in a valid UTF-8 string.

Passing true will forcibly tidy all bytes, assuming that the string's encoding is entirely CP1252 or ISO-8859-1.

# File lib/active_support/multibyte/chars.rb, line 197
def tidy_bytes(force = false)
  chars(Unicode.tidy_bytes(@wrapped_string, force))
end
titlecase()
Alias for: titleize
titleize() click to toggle source

Capitalizes the first letter of every word, when possible.

"ÉL QUE SE ENTERÓ".mb_chars.titleize    # => "Él Que Se Enteró"
"日本語".mb_chars.titleize                 # => "日本語"
# File lib/active_support/multibyte/chars.rb, line 152
def titleize
  chars(downcase.to_s.gsub(/\b('?\S)/u) { Unicode.upcase($1)})
end
Also aliased as: titlecase
upcase() click to toggle source

Converts characters in the string to uppercase.

'Laurent, où sont les tests ?'.mb_chars.upcase.to_s # => "LAURENT, OÙ SONT LES TESTS ?"
# File lib/active_support/multibyte/chars.rb, line 123
def upcase
  chars Unicode.upcase(@wrapped_string)
end